With Swarms of Ships, Beijing Tightens Its Grip on the South China Sea

The Chinese ships settled in like unwanted guests who wouldn’t leave.

As the days passed, more appeared. They were simply fishing boats, China said, though they did not appear to be fishing. Dozens even lashed themselves together in neat rows, seeking shelter, it was claimed, from storms that never came.

Not long ago, China asserted its claims on the South China Sea by building and fortifying artificial islands in waters also claimed by Vietnam, the Philippines and Malaysia. Its strategy now is to reinforce those outposts by swarming the disputed waters with vessels, effectively defying the other countries to expel them.

The goal is to accomplish by overwhelming presence what it has been unable to do through diplomacy or international law. And to an extent, it appears to be working.

“Beijing pretty clearly thinks that if it uses enough coercion and pressure over a long enough period of time, it will squeeze the Southeast Asians out,” said Greg Poling, the director of the Asia Maritime Transparency Initiative at the Center for Strategic and International Studies in Washington, which tracks developments in the South China Sea. “It’s insidious.”

called their presence “a clear provocation.” Vietnam’s foreign ministry accused China of violating the country’s sovereignty and demanded that the ships leave.

By this week, some had left but many remained, according to satellite photographs taken by Maxar Technologies, a company based in Colorado. Others moved to another reef only a few miles away, while a new swarm of 45 Chinese ships was spotted 100 miles northeast at another island controlled by the Philippines, Thitu, according to the satellite photos and Philippine officials.

intensifying confrontation between China and the United States.

Although the United States has not taken a position on disputes in the South China Sea, it has criticized China’s aggressive tactics there, including the militarization of its bases. For years, the United States has sent Navy warships on routine patrols to challenge China’s asserted right to restrict any military activity there — three times just since President Biden took office in January.

Secretary of State Antony J. Blinken expressed support for the Philippines over the presence of the Chinese vessels. “We will always stand by our allies and stand up for the rules-based international order,” he wrote on Twitter.

The buildup has highlighted the further erosion of the Philippines’ control of the disputed waters, which could become a problem for the country’s president, Rodrigo Duterte.

The country’s defense department dispatched two aircraft and one ship to Whitsun Reef to document the buildup but did not otherwise intervene. It is not known whether Vietnamese forces responded.

ruled in 2016 that China’s expansive claim to almost all of the South China Sea had no legal basis, though it stopped short of dividing the territory among its various claimants. China has based its claims on a “nine-dash line” drawn on maps before the establishment of the People’s Republic of China in 1949.

A Philippine patrol first reported the large number of ships at Whitsun Reef on March 7. According to Mr. Poling, satellite photographs have shown a regular, though smaller, Chinese presence over the past year at the reef.